1. Field of the Invention
This invention relates to parking brake mechanisms and more particularly to parking brake mechanisms of the type suitable to actuate a remote cable-operated brake mechanism.
2. Description of the Related Art
Parking brake mechanisms for actuating cable-operated brake mechanisms are known and used commercially in motor vehicles. An example of such a parking brake mechanism is disclosed in U.S. Pat. No. 5,211,072. The parking brake mechanism disclosed in the '072 patent includes a variable ratio lever arrangement and an automatic slack take-up system. The automatic slack take-up system includes a take-up reel to which is attached one end of the cable for operating the remote cable-operated brake mechanism. The take-up reel has fixed thereto a segmental ratchet member having a series of arcuately arranged ratchet teeth along an outer periphery thereof. The take-up reel and ratchet member are mounted on the actuating lever for movement about an axis which is disposed in spaced parallel relation to the pivotal axis of the lever. A spring-pressed pawl is pivotally mounted on the lever adjacent the ratchet member in a position to be biased into engagement with one of the ratchet teeth. An abutment pin carried by the frame on which the lever is mounted serves to hold the spring-pressed pawl out of tooth engagement when the lever is in the normal brake-releasing position thereof. A coil spring is connected between the take-up reel and the lever to bias the cable in a direction to tension the same and hence automatically apply a predetermined slack tension to the cable commensurate with the strength of the coil spring. When the lever is moved out of the normal brake-releasing position, the pawl moves away from the abutment and into engagement with a ratchet tooth to thereby prevent turning of the take-up reel and insure that the cable will be pulled with the lever to apply the brakes when the lever is moved into a brake-applying position thereof. Because the stoppage of the take-up reel must be accomplished by the engagement of the end of a pawl with a ratchet tooth, there exists the possibility that the pawl may engage just the very tip of a ratchet tooth rather than to be moved fully into the trough between two teeth for full tooth engagement. A tooth tip engagement of the pawl is susceptible of slipping from engagement of the tooth tip and allowing take-up reel movement to release the cable-operated brake mechanism before the pawl can be biased into full engagement with another tooth.